There is a demand to connect a large number of image processing apparatuses (printers, scanners, digital copiers, facsimile machines, and the like) via a network, operate the image processing apparatuses in a coordinated fashion, and thereby implement more advanced functionality. For that, it is proposed to convert (vectorize) image data exchanged among image processing apparatuses into resolution-independent image data format (resolution-independent data: vector data). The image processing apparatuses which receive the vector data convert (rasterize) the vector data into a bitmap image. Thus there is no image degradation due to resolution conversion. This makes it possible to generate bitmap images suitable for each image processing apparatus and thereby obtain high-definition images. In particular, this provides an important technique for mutually linking various image processing apparatuses which have different capabilities.
Also, it is proposed to manage information (metadata) which is not printed, as additional information on vectorized image data. The metadata, which contains information about image data, is intended to provide tips on image processing or keywords for use in image searches, and so on.
Furthermore, it is also proposed to perform an OCR process (optical character recognition process) on a bitmap image read from an original by a scanning apparatus and adds character codes obtained as OCR process results to image data, in the form of metadata so as to be used as image search information.
Besides, if the input image data is stored as a file in a secondary storage device of the image processing apparatus, a user can retrieve and output the image data repeatedly whenever desired. A feature which allows image data to be stored as a file in a secondary storage device of an image processing apparatus for the purposes of reuse of the image data is referred to as a box feature and a file system used for this is referred to as a box. The fox feature allows the user to repeatedly reuse image data once generated such as printing stored image data again or delivering the image data to an image processing apparatus with different capabilities. When large amounts of image data are stored in a distributed manner in such boxes installed on a large number of image processing apparatus connected via a network, it will be convenient if the image data can be searched. Conceivable search methods include a method which adds OCR process results (such as described above) in the form of metadata to image data in advance, searches for the metadata, and thereby finds desired image data quickly and easily. However, optical character recognition by the OCR process may have a high recognition errors rate depending on languages supported by OCR functions of the image processing apparatus as well as on OCR performance of the image processing apparatus, and the like. Therefore, a technique has been proposed which stores a region of an input bitmap image as it is without using an OCR process if it is likely that the OCR process will cause recognition errors in the given region (Japanese Patent Laid-Open No. 2000-339402).
However, with the conventional technique, even if a region is left in the form of a bitmap image because characters cannot be recognized correctly, another image processing apparatus with different OCR performance may be able to recognize characters correctly in the region. For example, copiers or printers of the same model are shipped to various language regions and their OCR functions support different languages. Thus, image processing apparatus intended for the English language may not be able to recognize characters correctly in an image containing Japanese characters. In that case, it is highly likely that proper OCR process results can be obtained if the image is transferred to an image processing apparatus capable of Japanese character recognition, if such is available. Also, if character size of an original is extremely small or characters are blurred, it is likely that an apparatus which has an OCR function with higher character recognition ability can recognize the characters more appropriately.
In this way, with the conventional technique, even if an image processing apparatus which can recognize a certain character string is available on the network, processing results of an OCR process are determined by the character recognition ability of an image processing apparatus which has happened to perform the OCR process. Consequently, even if another image processing apparatus has an OCR function with higher character recognition ability, it is not possible to make full use of the ability.